Insert bit structure



June 16, 1964 P. W. SCHUMACHER, JR

INSERT BIT STRUCTURE 2 Sheets-Sheet 1 Filed May 31, 1962 I NVEN TOR. M BY g 5.41% 7h, g

A I TO/PW VJ P. w. SCHUMACHERQJR 3,137,355

June 16, 1964 INSERT BIT STRUCTURE 2 Sheets-Sheet 2 Filed May 31, 1962 P. W. Jc/7u/27ac/2er I INVENTOR.

Unitad Slams PatdI O 7 3,137,355 INSERT BIT STRUCTUR Percy W. Schumacher, Jr.,- Houston, Tex., assignor t Reed Roller Bit Company, Houston, Tex., a corporation of Texas 1 Filed May 31, 1962, Ser. No. 199,074 Claims. (Cl.- 175-374) This invention relates generally to roller cutter type earth boring drills, and more particularly to the cutters used on such drills.

In the drilling of wells with roller type drill bits, the bit is connected to the lower end of a drill stem which is lowered and rotated to cause the cutters to roll upon the bottom of the borehole to cut or crush the formation being encountered. A drilling fluid, such as mud or air, is pumped downwardly through the drill stem and bit, and rises in the space between the drill stem and the wall of the hole to the surface of the earth, to remove cuttings produced by the drilling operation.

The roller cutters to which the present invention relates are those in which formation crushing inserts of hard metal, such as sintered tungsten carbide, are mounted in steel rollers.

The general object of this invention is to so combine the sintered tungsten carbide insert and the steel of the roller that the steel will provide a strong support for the insert and at the same time permit maximum penetration of the formation by the insert, and also free movement of the cuttings away from the insert.

Another object is to provide such a cutter in which the insert is mounted in a frusto-conical boss so that there will be a minimum of steel adjacent the outer portion of the insert, and streamline surfaces surrounding the insert, to the end that the drilling fluid may quickly remove the cuttings without premature erosion of the boss, as the insert efl'iciently penetrates the formation.

A further object is to provide such a boss having a relatively thin outer portion so that it is expansible for the reception of the insert.

Other objects will become apparent from the following description and accompanying drawings, in which:

FIGURE 1 is a bottom plan view of a drill bit employing the invention.

FIGURE 2 is a longitudinal sectional view, partly in elevation, taken along line 2-2 in FIGURE 1.

FIGURE 3 is an enlarged fragmentary view taken along line 33 in FIGURE 2.

FIGURE4 is a plan view of the roller cutting portion shown in FIGURE 3.

In the drawings, a well drill is shown generally at 1 comprising a bit head 2 having a hollow threaded shank 3 adapted to be connected to the lower end of a drill stem (not shown). A drilling fluid is circulated downwardly through the drill stem into a chamber 4, and issues through passageways 5 to the exterior of the bit to wash the cuttings and detritus from the bottom of the hole.

Referring to FIGURES 1 and 2, the drill bit 1 may employ approximately conical shaped roller cutters 6, 7 and 8. The bit head 2 has a downwardly extending leg 9 and a shaft 10 projecting downwardly and inwardly from the leg 9. The cutter 6 is rotatably mounted on the shaft 10 on ball bearings 11 and roller bearings 12. The ball bearings 11 may be inserted in place through a bore I 3,137,355 Patented June 16, I964 metal inserts 18'may be inserted into the gage face 19 of 1 the cutter-6 to assist in maintaining the gage of the bore-' hole as drilling progresses.

The'bosses 17 have a socket 20 drilled or otherwise provided in said bosses. A wear resistant insert 21tis preferably secured in the socket 20 by pressing the insert 21 into said socket which may be slightly smaller than the outside diameter of the insert. The relatively thin wall of the outer portion of the boss 17 will readily permit such insertion.

Referring to FIGURES 3 and 4, the frusto-conical boss 17 extends radially outwardly from the surface 16 of the cutter 6. Since the boss 17 is frusto-conical in shape, the insert 21 is uniformly maintained therein since a plane passed through the boss 17 normal to the axis of the insert 21 would result in a section wherein the cutter material of the boss 17 has a uniform section surrounding the insert thereby effecting a more uniform retention of the insert. 7

As can best be seen in FIGURE 4, the upper surface 22 of the boss 17 shows such uniform surrounding cutter material. The outside diameter of the outer end of the boss 17 is approximately one-third larger than the diameter of the insert 21. Thus as drilling progresses, the area i 22 presents a relatively small amount of steel to contact the formation being drilled so that deeper penetration of the sintered tungsten carbide insert 21 into the formation is afforded. p I

In certain formations, it may be desired to employ the frusto-conical bosses on the intermediate areas of the drill bit rollers only, but it is apparent that, depending on the formation being encountered, various arrangements of such conical bosses may be employed.

Since the boss 17 and its attendant insert 21 project a substantially from the surface 16 of the cutter 6 to provide streamline surfaces, it will be apparent that the drilling fluid issuing from the passageways 5 may more easily circulate away formation cuttings from thebottom of the borehole and from the areas around the cutters, and that premature erosion of'the bosses is prevented.

Thus the invention provides a structure wherein hard metal inserts may be placed in frusto-conical shaped,

bosses to provide a uniform support for the insert, and a minimum amount of boss surface surrounding the insert to permit deeper insert penetration into the formation to effect a higher drilling rate.

a conical cutting tip pressed into each said socket and into said body and extending outwardly from said flat circular surface.

2. The roller cutter structure as defined in claim 1 in which the outside diameter of the outer end of each boss is approximately one-third larger than the diameter of the insert.

3. The cutter structure as defined in claim 1 in which the roller cutter is a conical roller cutter. 7

4. The cutter structure as defined in claim 1 in which the roller cutter is a conical roller cutter and in which the outside diameter of the outerend of each boss is approximately one-third larger than the diameter of the insert. I i

5. A rotary well drill comprisinga head having inwardly and downwardly extending shafts on the bottom portion thereof, approximately conical roller cutters rotatably mounted on said shafts, each of the cutters comprising a body portion having a row of'frusto-conical bosses integral therewith and disposed therearound, eachboss terminating outwardly in a flat circular surface, each boss having a socket extending through said boss into said body portion, and a tungsten carbide Wear-resistant insert substantially cylindrical in its shank part and prov vided with a conical cutting tip pressed into each said socket and into said body and extending outwardly from said flat circular surface.

References Cited in the file of this patent Talbert et al.1 June 27, 1961 T 

1. A ROLLER CUTTER FOR A WELL DRILL COMPRISING A BODY HAVING A PLURALITY OF FRUSTO-CONICAL BOSSES INTEGRAL THEREWITH, EACH BOSS TERMINATING OUTWARDLY IN A FLAT CIRCULAR SURFACE, EACH BOSS HAVING A SOCKET EXTENDING THROUGH SAID BOSS INTO SAID BODY, AND A WEAR-RESISTANT INSERT SUBSTANTIALLY CYLINDRICAL IN ITS SHANK PART AND PROVIDED WITH A CONICAL CUTTING TIP PRESSED INTO EACH SAID SOCKET AND 